There is an increasing trend towards coatings containing nanoparticles being applied to webs to enhance their functionality and, in particular, their optical properties. These coatings are extremely thin and as such are very susceptible to defects caused by microscopic particles of contamination on the surface of the web. The only effective method of removing such small particles from the surface of sensitive webs is through the use of contact cleaning technology. However, because this involves touching the surface of the web with a cleaning roller there is an interfacial reaction between the roller and the substrate which can have a detrimental effect on the quality of extremely thin coated layers. There is therefore a growing need in contact cleaning technology to mitigate the interfacial reaction while providing particle removal down to the submicron level.
In particular, the growing markets for plastic electronics, photovoltaics and flat panel displays are driving the web coating industry towards the limits of current coating technology by demanding thinner, more consistent, defect free coatings. This level of quality can impact process yields and therefore increase costs for the coating company.
Contact cleaning in conjunction with adhesive rolls is commonly used to clean substrate surfaces in the manufacture of electronic components. For example, we refer to WO99/24178, WO2007/034244 and WO2008/041000 which are incorporated herein by reference. However, existing systems are not capable of efficiently removing small particles such as in the range of about 10 nm to about 10 microns (10,000 nm).
Whilst precautions can be taken to minimise surface contamination using, for example, air filtration to trap airborne dust particles, it is desirable to be able to clean surfaces in a manner that avoids damage to or dissolution of a substrate surface being cleaned, and is preferably easy to perform.
It is an object of at least one aspect of the present invention to obviate or mitigate at least one or more of the aforementioned problems.
It is a further object of at least one aspect of the present invention to provide a contact cleaning surface capable of providing improved cleaning to a contaminated surface.
It is a further object of at least one aspect of the present invention to provide a contact cleaning surface capable of collecting and/or removing microscopically sized contaminating material from a contaminated surface.
It is a yet further object of at least one aspect of the present invention to provide an improved contact cleaning method capable of providing improved cleaning to a contaminated surface.
It is a yet further object of at least one aspect of the present invention to provide an improved contact cleaning method capable of collecting and/or removing microscopically sized contaminating material from a contaminated surface.